The Orion Launch Abort System (LAS) is designed to carry the Orion spacecraft and its crew away from the rocket if a problem occurs on the launch pad after ignition or during ascent. Such launch abort scenarios feature highly complex fluid flows that need to be carefully analyzed to ensure the safety of the astronauts. We produced detailed turbulence-resolving simulations to help collaborators on the Orion Loads and Dynamics team assess key aspects of the launch abort environment: the strength of ignition overpressure waves and the levels of acoustic vibrations generated by the hot plumes. Using the Launch, Ascent, and Vehicle Aerodynamics (LAVA) software’s Cartesian Adaptive Mesh Refinement (AMR) capability, we were able to accurately reproduce ground test and wind tunnel test measurements and trends. We then performed a number of simulations exploring different abort scenarios to help reduce uncertainty in areas where experimental data was not available, within a short enough turnaround time to have an impact on the design of the LAS.
Biography
Francois Cadieux is a research scientist in the Computational Aerosciences Branch of the NASA Advanced Supercomputing Division at NASA Ames Research Center. He received the NASA Early Career Public Achievement Medal in 2018 for enhancing the safety and success of the Orion Launch Abort System through high-fidelity computational aero-acoustic predictions of the QM-1 test and launch abort scenarios. Cadieux joined the Launch Ascent and Vehicle Aerodynamics (LAVA) group in September 2016. He completed a postdoctoral fellowship at the Flow Physics and Computation Lab under the supervision of Prof. Rajat Mittal at Johns Hopkins University from 2015 to 2016. His research focused on developing and validating wall-modeled large-eddy simulation (LES) for separated flows. Cadieux also investigated the dynamics of active flow control to mitigate flow separation and delay stall. During his graduate work with Prof. Julian A. Domaradzki, Cadieux probed the limits of under-resolved LES for separated flows applicable to small unmanned aerial vehicles and low pressure turbines, and quantified the importance of numerical dissipation effects when performing LES on such coarse grids. He obtained his Ph.D. in aerospace engineering from the University of Southern California in 2015.
